PROJECT ABSTRACT/SUMMARY Traumatic brain injury (TBI) is the most common cause of death in childhood. The predominant etiologies of TBI in young children are motor vehicle accidents, firearm incidents, falls, and child abuse. Unfortunately, falls are the leading cause of non-inflicted head injury in infants less than a year old, and are also the most common history provided by caretakers suspected of child abuse. Some cases are easy to diagnose, but in cases of uncertainty accurate diagnosis of inflicted trauma is hindered by a lack of clarity regarding specific head injury mechanisms for young infants. The objective of this research proposal is to provide clinicians with a biomechanics-based tool to aide in the diagnosis of inflicted or non-inflicted trauma with a history of a low- height fall. In Aim 1, biomechanical tolerances of extra-axial hemorrhage (subdural and subarachnoid hemorrhage) are determined by using a porcine computational model to simulate non-impact rapid head rotation experiments in 3-5 day old piglets. Mechanical responses from the model (cortical displacement relative to skull and peak cortical tissue strain) are statistically correlated with the actual occurrence of extra- axial hemorrhage (EAH) on the piglets'cortex to identify biomechanical tolerances associated with 10, 50 and 90 percent probability of EAH. To validate this tolerance and determine probability thresholds with the greatest specificity and sensitivity to predicting EAH in cases of well-witnessed falls, a human infant computational model is developed in Aim 2 to predict the brain and skull response to impact. Simulating well-witnessed cases of falls in infants, the biomechanical tolerance for EAH in Aim 1 and a biomechanical tolerance for skull fracture previously published from our lab are used to determine the probability of skull fracture and EAH most predictive of the injuries in each of the case simulations. To measure loads in common household fall settings, a 1 1/2 month old human infant biofidelic surrogate is used in Aim 3 to recreate falls from 1, 2, and 3 feet onto carpet, concrete, hardwood, tile, and linoleum to simulate common household fall settings. Impact force and angular accelerations for ten repetitions of each height, surface, and primary head impact location (parietal or occipital) are obtained, creating a load corridor for each fall scenario. Combining the biomechanical loads from the surrogate experiments, existing pediatric large animal TBI data, and a new biofidelic computational model of the brain and skull of a human infant, a predictive tool to is created in Aim 4 to determine the plausibility of skull fracture and extra-axial hemorrhages (EAH) in infants following low height falls. Validated with real-word clinical data, this biomechanical data will advance the understanding of injury thresholds in common non- inflicted scenarios that will ultimately improve the accuracy in detection of inflicted and non-inflicted head trauma. National objectives from Healthy People 2010 calls for a reduction in child maltreatment, a reduction in fatalities caused by child maltreatment, a reduction in unintentional injury and a reduction in deaths from falls. Developing a clinical tool that is biomechanically sound and informs clinical practice will directly contribute to the fulfillment of these national health and welfare priorities. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE Our proposed research plan will advance the understanding of injury thresholds in common non-inflicted scenarios that will ultimately improve the accuracy in detection of inflicted and non-inflicted head trauma. There is no topic greater than pediatric abusive head trauma that evokes controversial discussion focusing on the emotional, medical, and legal aspects of misdiagnosis. Our plan is consistent with the national objectives from Healthy People 2010, designed to contribute to a reduction in child maltreatment, a reduction in fatalities caused by child maltreatment, a reduction in unintentional injury, and a reduction in deaths from falls.